Automatic switch



H. F. OBERGFELL AUTOMATIC swITcH Filed Aug. e, 41928 2 Sheets-Sheet lApril ri4, 1931. H. F, oBERGf-'ELL AUTOMATIC SWITCH Filed Aug. 6, 1928 2Sheets-Sheet 2 ell Patented Apr. 14, 1931 A Unirse stares PATENT OFFICEHERBERT F.'OBERGFELL, OF RIVER FOREST, ILLINOIS, ASSIGITOR TG RESERVEHOLDING COMPANY, F KANSAS CITY, MISSOURI, A CORIORATION OIE DELAWAREAUTOMATIC SWITCH Application led August 6, 1928.

VThe invention in this application relates in general to automatictelephone systems, but more particularly, it relates to the automaticswitching devices employed in such a System for establishing talkingconnections between calling subscribers lines and called subscriberslines.

The lparticular switch concerned in this Iapplication is what iscommonly known asa l@ plungertype lineswitch, being a switch of thenon-numerical type which is individual to asubscribers line and operatesto connect theV calling subscribers line to an idle one of a oup ofswitches common to a number of su scribers lines and comprising thefirst numerical switch of the switch train.

. In the past it has been necessary in systems where plunger type lineswitches are used, to employ a master switch for controlling the zomovement of the plungers of the lineswitches. Since the functions of themaster switch are well known, they will not be described since themaster switch itself, does not constitute a part of the presentinvention.

In systems of only a few lines, the provision of a master switch entailsconsiderable expense, so I have assumed as the principal ob- ]ect ofthis invention the provision of an individually driven plunger typelineswitch,

0 thus eliminating the necessity of having a master switch.

One'feature lies in the arrangement for controlling the movement of theplunger in seeking an idle trunk after the removal of the callingsubscribers receiver from the switch hook preparatory to the operationof the calling device, whereby the plunger hunts in both directions foran idle trunk, that is, from trunk 1 to 1() and then from trunk 10 to l.y

i Other objects and features will be apparent from a. perusal of thedetailed description and claims which follow, when taken in conejunction with the drawings in which- Fig. 1 is a top view of the switchassembly; Fig. 2 is a sectional view of the plunger and bank taken alongthe line 2-2 looking from the left;

Fig. 3 .is a diagrammatic showing of the operating circuit of thelineswitch.

Serial No. 297,829..

A detailed description of the construction of the switch will now begiven, reference being had particularly to Fig. 1.

Similar numerals refer to similar parts throughout the several gures.

Reference numeral 4 indicates the mounta ing plate upon which all of theequipment of the switch is mounted. The switch bank 5 is similar inconstruction to that shown and described on page 38 of Vol. II of thebulletin entitled Principles of Automatic Telephone by Harry P. Mahoney,which bulletin is published by the Automatic Electric Inc., of Chicago,Illinois. This bank is mounted and held in position by the posts 6 and 7which are rigidly screwed to the plate 4 from the back side. This bankis provided with an extra set of ten contacts 8 which protrude from thebank assembly on the side nearest the plate 4 and parallel thereto. Thepurpose of these contacts will be explained a little later.

Located in front of the contact bank is the disc 9 which is rotatablymounted on the plate 4, being separated therefrom by a thick washerwhich is not visible in the drawings. The disc 9 is held on the pivotshaft by nut 10.

Rigidly fastened to the underside of the disc 9 is a ratchet wheel 11(shown dotted) which has for its purpose the rotating of disc 9.

Cut to a depth of approximately oneeighth of an inch in the uppersurface of the disc 9 is the heartfshaped channel 12. The purpose ofthat channel will be explained later.

The plunger 13 is mounted on the plate 4 by means of a standard (notvisible) which is of such a size as to hold the plunger above the disc,the plunger being pivotally mounted on the standard at 14. The plunger13 is made 'up of two flat pieces 15 and 16, with 16 lying on top of 15.The end of parts 15 `and 16 are shown in Fig. 2. Piece 15 carries thepivot 14 and its only motion ,is a rotary motion about. the pivot 14. Tothe underside of the piece 15 is fastened the roller 17 which. rides inthe channel 12 of disc 9. On the upper side of 15 are the two smallposts 18 and 19. Member 16 has two long slots in y eo.

o 'which tiw'seftwo postent. The tops of the postsare wider than theslots to prevent 16 Y from separating from 15.` VWith this arrange'-lment 16`is slidable along 15. The' end of 16Av which is adaptedtooperate the springs of the contact bank is arrow shaped and carries theroller bushings 20, best seen in Fig". 2.

l. operating magnets 22 Vof the switch. rlheV On'the'underside of 15 isrigidly fastened lthe vwiper21 which is so placed as to rub thecontactsrotated. Y .i 1., 'I o the left of the disc is Ylocatedone Aof theSoffthe bank'as plunger 13 `is heel piece of this magnet is fasteneddirectly near, oneV of` its ez'tremities.y

g Vto plate 4 by means yof screws." This magnet and jwhenfthe Ymagnet,deenergizes thepawl tated given amount, the motive l Vpower beingprovided sprin" 2fastened to the plate 4 and to the end o armature23.``The stopu27 .,is engagedgbygpawl 24 limitingthe movement of the pawland locking it in the teeth of the ratchet. Spring v28V holds V'pawl 24vagainst the teethduringits movementjY s The iopposite iend` .offthearmature. 23 Vis the spring 29 l f ergizationofimagnet 22.

' vent reverse, or clockwise,

disc It is Vfastened to bracket 37 vWhichin turn is fastened, to the i i,providedwithabushing toinsulateit from. whichitoperates upon Aeach en.-

. ;Res ili ent member y36jis employed toifipremovement of the 'j To`lthe iight oithe disc9 isanother'opf erating relay VThe heel. piece'ofthis relay is rigidly secured to the. plate :4. Relay 30 is provided`with two armatures,v pull-down armature 131 and bridge-cut-oii'varmature 32.

usual manner tothe heelpiece at 33.., A n aperture in ,thearmatnre, 31allows the? bent i through itto completea closed ,cuit withthe coreofthe relay. A. i 1 One end of the armature 31 is' made fork -shapedasshown in the-drawings; rllhe over, position Yof'the'armature 32Jto' passprongs A of Vthis fork f it ,one on either ,side of fthe pin "34.fwhichis "secured to Vthe .member 1 6 of plunge`r13. Resilientmember35'ifco-,jv operateswith" the v.other end ofarmature31 to holdfthfarmature away from the yendVV of the l core when therelay is notenergized.`

:The end ofthe-BCOv armature not in the magnetic circuit is use d intheusualmanner to `ope-ratev springs.

When theV pull-down armature is attracted jtothejcore'qof thereby, the-vmember16 is moved 0n-:fthe member 15 and'plungedinto @Q -haakte .QrerheContests@ the Well,

of ratchet. Ar;

= the right.. angle y Bothoff these"armatures are pivoted inthe switch.

magnetic cir known-manner. The normal .position of armature '31 holdsthe plunger out of the bank. Screw 38 is used as axbackstop for arma-vture 31 andit is threadedinto a'portion of the heel thesplate 4. v sIi"l it is desired to rotate the plunger 13 to piece whichisbent-upwards from seek an idle trunk,rcircuit connections will energizemagnet 22. This magnet thenattract's its armature 23 thereby'movingthepawl. 24

into'engagement with` the tooth next: to that withv which it wasjatVthat time engaged. Whenthe-magnet 22 is'deenergized, armature 23retracts, and 'under the influence of spring '26, pawl 24 rotates thedisc 9one step yin a counter clockwise direction. vThe y.rotation ofdisc 9 throughthe actionof roller 17 rolling in channel 12, thesidesloffwhich: actas la cam, rotates the plunger 13 lone step aboutpivot v14,'

In vthe position in whichv thef'disc 9:.is shown the direction ofrotation ofplungery 13 isre versed. At this point,`the plungerisstanding opposite thejleft hand set ofcontacts ofbank 5. `Thus it canybeseen that theA 'rotation of disc 9 in one direction will-causetheyrotation of plunger 13 in bah directions, thus moving from trunk 1 totrunk 10 and then fromftrunk -v inthe drawing, that iotatioii'i s in ,a'counter .clockwise f direction. Y When'` .the roller=, passes the endLoi. theheartgshaped channel,

10to trunk. 1 lstopping'atfidle trunksbe tween.

v The` bank and wiper 'arrangement shown in s Fig 2'W11'mwbe XPlened.Theupper 'of thepaiaef. contactsS-in Qaoh Se@ thevrghb hand one inF ig.2, take the place ofa contact similar to the contact 3 9, being madelonger so as to protrudel fartherfrom the bankso that wiper 21 can makea Ywiping contact ,with it and with its associate vcontact. Q'Afpairof Vthese contacts V8v are provided Vfor each trunk andare the testcontactsofthetrunks acces- Vsible' to Athis switch, ground being fconneotedtothis contact when rthe associated trunk is use to prevent seizureofthe any line It will bey noted that the spring 40.v when operated-bythe plunger makes Contact with one ofthe set ofcontaet's 8. 5, 'AVdescri tionjof the constructionV of Vthe switch having been given, avdetailed ydescrip- Vtionof the operation willnowbe related, Treferencebeing [had lpartieularly5to Fig. 3.' In

that ngure, LS designatesfthe individually driven lineswitch ofthisapplication vconductors 42 and 4 4 areV thejline Vconductors confnecting the line `switch to the subscribers station towhit'zhl iti'sindividllal "which vhas the usual talking, `receivingand signal# linginstrumentalities andf'lwhich is also equipped with a welllknownimplulse sender yor calling device, Vthey Y substation equipmentnot being shownon the drawingfor sake of simplicity; y,the privateconductor 43 which is multimedia the banks e5. all@ 0f.1e.',fl11a1connector switches having access to that substation; and the selector Ewhich is of the well known type of Strowger selector having wipersadapted to be moved in a vertical direction and thence a rotarydirection under control of the calling device at the substation, onlyenough of the selector being shown which is necessary vfor anunderstanding of this invention.

When the subscriber desires to initiate a call, he removes his receiverfrom the hook and in so doing he completes a loop circuit including thereceiver and transmitter in series with the line conductors 42 and 44.The closure of the loop circuit completes a circuit Jfor line relay 45of lineswitch LS. This circuit is traceable from ground through the lefthand set of contacts of the off-normal springs, conductor 47, conductor44, over the subscribers loop circuit, conductor 42, conductor 46, righthand Contact set of olf-normal springs, winding of line relay 45 togrounded battery. Relay 45 energizes in that circuit and operates itsarmature to move the associated springs into engagement with their makecontacts. The engagement of spring 48 with its grounded make contactplaces ground on the test contacts associated with that line in thebanks of the connector switches having access thereto, by placing groundon conductor 43. The engagement of spring 49 with its make contactcompletes a circuit for relay 51 and magnet 22 in series. The engagementof spring 50 prepares a circuit joined between the relay 51 and magnet22.

The operation of this switch from this point on depends upon the trunkcondition, that is, whether or not the trunk opposite which the plungerof the lineswitch is standing is idle. It will rst be assumed that it isidle, in which case the relay 51 will operate when its circuit iscompleted. Relay 51 is of ai high enough resistance as to prevent magnet22 energizing in series with it.

The operation of relay 51 moves its spring 52 into engagement with itsgrounded make contact thereby completing the obvious circuit or thepull-down winding ot operating relay 30, which winding energizes andattracts its two armatures 31 and 32. The operation ot pull-downarmature 31 plunges the plunger into the bank thereby causing springs 53and 54 to engage springs 55 and 56 and spring 40 to engage spring 8. Theoperation otbridge cut-oli armature 32 moves the ott-normal springs outof engagement with their back contacts thereby opening the circuit otline relay 45 which deenergizes and-opens the circuit of relay 51. Relay51, because of the copper slug on the heel end of its core, is slow torelease and remains energized an interval after its circuit is opened.

The engagement ot springs 53 and 54 with springs and 56, respectivelycompletes the follwing circuit Jfor line relay 64 ot selector Fromground, through the lower winding of relay 64, conductor 63, backContact and spring 61 of switching relay 69, conductor 59, spring 56,spring 54, conductor 44, substation loop circuit, conductor 42, spring53, spring 55, conductor 58, spring and its back contact, conductor 62,and upper winding of relay 64 to grounded battery.

Relay 64 operates in that circuit and moves its spring 65 intoengagement with its front contact, completing the circuit of releaserela",7 66 which energizes and at its spring-67 places ground on releasetrunk conductor 68. That ground is extended to the BCO winding of relay30 via contact 8 and spring 40 before relay 51 deenergizes.

Then relay 51 deenergizes it opens the circuit ot the pull-down windingof relay 3() at 52. However, armatures 31 and 32 will be held attractedby the BCO winding of relay 23.

The ground on conductor 68 will also be extended to conductor 43 tosubstitute tor the ground removed therefrom when relay 45 deenergized.

The selector E may now be controlled by the calling device for extendingthe connection to the next switch in the switch train in the well knownmanner.

It will be assumed now that when the line switch LS was seized, itsplunger was standing opposite a busy trunk, in which case a groundpotential would be present upon the set of contacts 8 associated withthat trunk. That presence of ground will be conducted to magnet 22 viawiper 21, conductor 57, and spring 50 and its make cont-act. Thus magnet22 will energize and interrupt its energizing circuit by moving spring29 out of engagement with its make contact. Magnet 22 deenergizes androtates the plunger 13 (Fig. 1) and wiper 21 to the next set of contactsas has previously been explained. Ground on conductor 57 will shortcircuit relay 51 before it has had a chance to operate, thus preventingrelay 51 from operating and plunging the plunger in the bank to connectthe calling subscriber to a busy trunk.

It the next trunk should be busy, wiper 21 will encounter ground againand magnet 22 will energize and deenergize to again adv gnce theplunger. When an idle trunk is encountered, noted by the absence ofground on the associated set of contacts 8, relay 51 will not beshortcircuited and it will operate as previously described.

At the termination of the call, the replacement ot' the receivers opensthe substation loop circuit and the switches release, removing groundfrom conductor 68, thus opening the circuit of the BCO winding of relay30 to release the armatures 31 and 32 to remove llO theplunger fromtheibank 4and prepare the `switchfor another call.

' --When the line switch `LS. is. seized by a Connector switchy onycalls incoming to the substation vassociated with LS, the connectorWill connect ground tol conductorrt to energize theBCO. winding offrelay8O to optlictsl` .v f 2. In an automatic switch, a normally staf l crateonly the Varmature 32, thereby opening the off-normal: springsf'tokprevent vthe re` Y lo moval ofthe-lreceiverrom the switch-hookcompleting the' circuit of the line lrelay 45'.

Having thus described .my invention, what YIconsider newanddesireto haveprotected Vby Letters Paten-ti is i pointed out in the appcndedclaims."`a

-YW-hatis claimed is: i'

(1,. The icombination,within a plunger type.

lineswitch," of a plurality of sets of bank contacts,vmeans Vforrotating VVthe plunger to position it opposite.` the bankcontacts oi''an idle trunk after Ltheseizureof the .switch by ay calling line,:Withfmeans for plunging the plunger intothe vbank to operatesaidcontionary,A plunger, abank lcomprising sets of Y contacts adapted to beoperated by the plunger, eachlcontact set-.being'the terminus of atrunlnmeans forrotating ysaid plunger step-v l by-step ,to positionitxop'posite thejcontact Vvset of an idle trunk,.and`xmeans responsive.tosaid .positioning for. plunging the plunger intosaid-'bank tooperatesaid contacts.`

3. lnffanautomaticv switch,a plunger, ay

`V`sgjfbank comprising setsiof contacts adapted to be 'operated `by saidplunger, each vcontact set being theterm-inus of a trunk, a test contactf 'associatedv with each contact set, a wiper carried by said .plungerandV adapted lto wipe saidtest contacts, each test contact having groundpotential thereon when the associated Vtrunk is; busy, meansresponsiveto the end counteringof 4ground potential by said wiper whenthe switch lis seized by `a calling vline for positioning said plungeropposite a contact setwhose associated test contact has not groundvpotential thereon, and means responsive '.tofsaidi-positioning forkplunging said plunger into thebank to operate said contacts..v 4.' Inanautomatic switch, a pivoted'plunger, ,a bank comprising: sets ofcontacts, each' setbeing the terminus Vof a trunlnarotatable eccentric,means for rotating` said eccentric to rotatesaidl-plunger about itspivot, to posi-A tion it. opposite ythe contact set of an lidle trunk,said-eccentric being of such shape as to rotate said plungery rst in onedirectionthen in another, 'and means responsive to said'po sitioningptoplunge said plungerlinto said d bank to operate said contacts.'

i' In anl automatic switch,a pivoted plung-y er, abank'comprising-'setsof' contacts, each set being the terminus of a trunlga rotatable Y discpivoted at its` center, a channel eccentri` trunk terminating in af-setof contacts individual thereto and adapted to be'operatedby.saidxplungenmeans in saidswitch and.

operated responsive to the initation of a call on saidfline forpositioning theplungeropposite the contact set of 'anidle trunk, andmeans in said switch for plunging'said plungerl into the *bank .to"operate Y said springs to connect! saidline tolileidle trunk.

7." In an automatic switch, a pivotedffplunger, Va bank comprising setsof contacts, each set'being the terminus of a trunk, a rotatable cam,means for'driving saidrcam continuously in one Idirection tojrotate saidplunger in *both*v directions `of rotation'to position itvoppositefthecontact set of anfidle trunk, and means vresponsive to said positioning.to plunge said plungerv into said bank to operate sail contacts."

r8: VIn an` automatic/switch, a plunger, a baul; comprising sets ofcontacts adapted to be'operated: by said plunger,'eachcontact set beingthe'terminus of an outgoing-trunk, said plunger standing opposite thetrunk last used when the switch is idle, meanswithin saidy switch-andresponsive tothe seizureof` the switchl byfa calling line -for plungingsaid plunger tolV operate thefcontacts of the trunk opposite which, itis standing if .that trunk is idle, and'means within saidy switch forrotat-y ing'said A.plunger to position' it opposite the contact setvolii an idletrunk if the ytrunk opposite which Vit is standing isbusy,said lastmeans preventing theop'eratio-n of said irst means untilsaidpositioning takes place.

9. In combination, within an-individual line switch, a plunger lfor'operating bankcontacts, electromagnetically controlled means forrotating the vplunger to position it1opposite theY bankf contacts of an;idle trunk-"after the lseizure of the switch by the'associated callingline, and electromagnetic vmeans for plunging''saidy plunger into theb'ankto operfV v ate said contacts; i Y n .i

10;" In an automatici switch, 'ya pivoted plunger, a bank comprising Vsets lof contacts,

each set ybeing the lterminusfof-'aitrunkv andV adapted to be'v operatedrby said"plunger, means within said switch for rotating said plungerstep-by-step in' bothl directions of rotation to position it; `oppositethe contactlset of an idle trunk, and means responsive to saidpositioning for plunging said plunger into the bank to operate saidcontacts.

11. In a telephone system, a subscribers line, an automatic switchindividual to said line, said switch having a plunger and a test wipercomprising a unitary structure, a bank comprising sets of contacts, eachset being the terminus of a trunk and comprising contacts adapted to beoperated by said plunger and an auxiliary contact to be wiped by saidwiper, said auxiliary contact having ground potential thereon when theassociated trunk is busy, means for rotating said unitary structurestep-by-step when said subscribers line initiates a call and as long assaid wiper encounters ground potential on said auxiliary contacts, toposition the plunger opposite the contact set of an idle trunk, andmeans responsive to the failure of said wiper to encounter ground on anauxiliary contact for plunging said plunger to operate the othercontacts of the set to connect said subscribers line to the idle trunk.

12. In an automatic switch, a set of contacts including line contactsand a test contact, a carriage provided with a wiper and a plunger,means for rotating said carriage to place said wiper in contact withsaid test contact, and separate means for plunging said plunger intosaid contact set to operate said line contacts into engagement with eachother.

13. In an automatic switch, a set of contacts including pairs of linecontacts and a test contact, a carriage provided with a plunger and awiper, means for rotating said carriage to position said wiper in.contact with said test Contact, and means responsive to saidpositioning for operating said plunger to operate the line contacts ofeach pair into engagement with each other, said last means preventingthe further operation of the rst means to hold said wiper in Contactwith said test contact.

14. In an automatic switch, a bank comprising sets of contacts, each setincluding line contacts and a test Contact, a carriage provided with awiper and a plunger, means Vfor rotating said carriage to wipe saidWiper over said test contacts to find an idle contact set, and separatemeans responsive to the nding of an idle contact set to plunge saidplunger into said bank to operate the line contacts of the idle set intoengagement with each other.

In witness whereof, I hereunto subscribe my name this second day ofAugust, A. D.

HERBERT F. OBERGFELL.

